Unix Timestamp Converter
Convert a Unix timestamp to a human-readable date, or a date back to epoch seconds — live, in your browser. Nothing is uploaded.
- ISO 8601
- UTC string
Runs entirely in your browser — nothing you enter is uploaded or stored.
How to use this converter
- Type a Unix timestamp into the left field, or a date into the right field.
- The other field updates live as you type — no button to press.
- Switch the unit selector between seconds and milliseconds if needed.
- Click Now to fill in the current epoch time.
What is the Unix epoch?
The Unix epoch is the reference point — 00:00:00 UTC on 1 January 1970 — from which Unix time is measured. A Unix timestamp counts the seconds (or milliseconds) that have elapsed since that instant, giving every point in time a single, unambiguous number.
Seconds vs. milliseconds
Most systems (Unix, PostgreSQL, PHP) use whole seconds since the epoch,
while JavaScript's Date.now() and many web APIs use
milliseconds. Mixing the two up is a common bug — 1700000000 read as
milliseconds lands in January 1970 instead of November 2023. This tool's
unit selector makes the conversion explicit either way.
UTC and timezones
A Unix timestamp has no timezone of its own — it's simply seconds since a fixed instant. Displaying it as a date always requires picking a timezone; this tool shows results in UTC, the zero-offset baseline every other timezone is defined relative to.
Related tools
- Epoch to Date converter — a focused epoch → date view.
- Date to Unix Timestamp — a focused date → epoch view.
Frequently asked questions
- What is a Unix timestamp?
- A Unix timestamp (also called epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970 — the "Unix epoch". It is a single number that unambiguously represents a point in time, independent of timezone or calendar format.
- Why do developers use epoch time instead of dates?
- A plain integer is trivial to store, compare and sort, and it sidesteps timezone and locale ambiguity entirely. Databases, APIs and log files overwhelmingly store time this way, converting to a human-readable date only for display.
- Seconds or milliseconds — how do I know which one I have?
- Check the number of digits. A current Unix timestamp in seconds has 10 digits (around 1.7 billion); in milliseconds it has 13. If your number looks like 1700000000 it's seconds — if it looks like 1700000000000 it's milliseconds. Use the unit selector above to switch.
- Does this tool account for timezones?
- The date output is always shown in UTC, which is what a Unix timestamp inherently represents. If you need a local timezone, convert the UTC result using your OS or a timezone-aware tool afterwards.
- Are my timestamps sent to a server?
- No. All conversion happens in your browser with plain JavaScript — nothing you type here is uploaded, logged or stored anywhere.
- What is the "Now" button for?
- It fills the epoch field with the current Unix time (in whichever unit — seconds or milliseconds — is currently selected), so you can quickly see or copy "right now" as a timestamp.
- Can a Unix timestamp be negative?
- Yes — a negative value represents a date before 1 January 1970. This tool handles negative timestamps correctly, converting them to the matching pre-1970 UTC date.